Thèses sur le sujet « INTERFACE TEMPERATURE »
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1
Karademir, Tanay. « Elevated temperature effects on interface shear behavior ». Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42764.
Texte intégralRésumé :
Environmental conditions such as temperature inevitably impact the long term performance, strength and deformation characteristics of most materials in infrastructure applications. The mechanical and durability properties of geosynthetic materials are strongly temperature dependent. The interfaces between geotextiles and geomembranes as well as between granular materials such as sands and geomembranes in landfill applications are subject to temperature changes due to seasonal temperature variations as well as exothermic reactions occurring in the waste body. This can be a critical factor governing the stability of modern waste containment lining systems. Historically, most laboratory geosynthetic interface testing has been performed at room temperature. Information today is emerging that shows how temperatures in the liner systems of landfills can be much higher.
An extensive research study was undertaken in an effort to investigate temperature effects on interface shear behavior between (a) NPNW polypropylene geotextiles and both smooth PVC as well as smooth and textured HDPE geomembranes and (b) sands of different angularity and smooth PVC and HDPE geomembranes. A temperature controlled chamber was designed and developed to simulate elevated temperature field conditions and shear displacement-failure mechanisms at these higher temperatures. The physical laboratory testing program consisted of multiple series of interface shear tests between material combinations found in landfill applications under a range of normal stress levels from 10 to 400 kPa and at a range of test temperatures from 20 to 50 °C.
Complementary geotextile single filament tensile tests were performed at different temperatures using a dynamic thermo-mechanical analyzer (DMA) to evaluate tensile strength properties of geotextile single filaments at elevated temperatures. The single filament studies are important since the interface strength between geotextiles and geomembranes is controlled by the fabric global matrix properties as well as the micro-scale characteristics of the geotextile and how it interacts with the geomembrane macro-topography.
The peak interface strength for sand-geomembrane as well as geotextile-geomembrane interfaces depends on the geomembrane properties such as hardness and micro texture. To this end, the surface hardness of smooth HDPE and PVC geomembrane samples was measured at different temperatures in the temperature controlled chamber to evaluate how temperature changes affect the interface shear behavior and strength of geomembranes in combination with granular materials and/or geotextiles. The focus of this portion of the experimental work was to examine: i) the change in geomembrane hardness with temperature; ii) develop empirical relationships to predict shear strength properties of sand - geomembrane interfaces as a function of temperature; and iii) compare the results of empirically predicted frictional shear strength properties with the results of direct measurements from the interface shear tests performed at different elevated temperatures.
2
Berber, Feyza. « CMOS temperature sensor utilizing interface-trap charge pumping ». Texas A&M University, 2005. http://hdl.handle.net/1969.1/4157.
Texte intégralRésumé :
The objective of this thesis is to introduce an alternative temperature sensor
in CMOS technology with small area, low power consumption, and high resolution
that can be easily interfaced. A novel temperature sensor utilizing the interfaceâÂÂtrap
charge pumping phenomenon and the temperature sensitivity of generation current
is proposed.
This thesis presents the design and characterization of the proposed temperature
sensor fabricated in 0.18õm CMOS technology. The prototype sensor is characterized
for the temperature range of 27oCâÂÂ120oC. It has frequency output and exhibits linear
transfer characteristics, high sensitivity, and high resolution. This temperature sensor
is proposed for microprocessor thermal management applications.
3
MOISELLO, ELISABETTA. « Integrated Interface Circuits for MEMS Contact-less Temperature Sensors ». Doctoral thesis, Università degli studi di Pavia, 2020. http://hdl.handle.net/11571/1370177.
Texte intégralRésumé :
Thermal sensors, exploiting the relation between the thermal radiation emitted by an object and its temperature, as expressed by the Stefan-Boltzmann law, allow realizing contact-less temperature measurements, required in a wide range of applications, ranging from fever measurements to presence detection for security and climate control systems.
With the advent of smart homes and Internet of Things (IoT) and the wide spreading of mobile and wearable devices, the need for low-cost low-power thermal sensors has arisen, therefore moving the focus of the research away from standard bolometers and pyroelectric detectors and towards uncooled infrared (IR) sensors solutions that can be easily integrated. Bolometers and pyroelectric detectors, which are the main types of thermal sensors found nowadays on the market, in fact, do not comply with the low-cost and easy integration specifications.
Integration of thermal sensors is possible through Micro-Electro Mechanical Systems (MEMS) technology, which allows combining on the same substrate or chip both electrical and mechanical structures with dimensions in the micro-meter range, thus providing structures with high thermal isolation and low thermal mass. The micromachining processes that are required to thermally isolate the sensing element from the substrate are versatile and include anisotropic wet etching, dry and wet etching, electrochemical etch stop, or the use of silicon-on-insulator (SOI).
In this scenario, STMicroelectronics has fabricated two different novel thermal sensors, which fulfill the low-cost low-power specifications for smart homes, IoT and mobile and wearable devices, while also being compatible with CMOS processes and thus easily integrated: a polysilicon thermopile and a micromachined CMOS transistor, from now on referred to as TMOS.
During my Ph.D. activity I was involved in a cooperation between the STMicroelectronics Analog MEMS and Sensors R&D group and the University of Pavia, that led to the design of two readout circuits specifically tailored on the sensors characteristics, one for the thermopile sensor and one for the TMOS (developed by the Technion-Israel Institute of Technology), which were integrated in two test-chip prototypes and thoroughly characterized through measurements as stand-alone devices and as a system with the sensor they were designed for.Thermal sensors, exploiting the relation between the thermal radiation emitted by an object and its temperature, as expressed by the Stefan-Boltzmann law, allow realizing contact-less temperature measurements, required in a wide range of applications, ranging from fever measurements to presence detection for security and climate control systems. With the advent of smart homes and Internet of Things (IoT) and the wide spreading of mobile and wearable devices, the need for low-cost low-power thermal sensors has arisen, therefore moving the focus of the research away from standard bolometers and pyroelectric detectors and towards uncooled infrared (IR) sensors solutions that can be easily integrated. Bolometers and pyroelectric detectors, which are the main types of thermal sensors found nowadays on the market, in fact, do not comply with the low-cost and easy integration specifications. Integration of thermal sensors is possible through Micro-Electro Mechanical Systems (MEMS) technology, which allows combining on the same substrate or chip both electrical and mechanical structures with dimensions in the micro-meter range, thus providing structures with high thermal isolation and low thermal mass. The micromachining processes that are required to thermally isolate the sensing element from the substrate are versatile and include anisotropic wet etching, dry and wet etching, electrochemical etch stop, or the use of silicon-on-insulator (SOI). In this scenario, STMicroelectronics has fabricated two different novel thermal sensors, which fulfill the low-cost low-power specifications for smart homes, IoT and mobile and wearable devices, while also being compatible with CMOS processes and thus easily integrated: a polysilicon thermopile and a micromachined CMOS transistor, from now on referred to as TMOS. During my Ph.D. activity I was involved in a cooperation between the STMicroelectronics Analog MEMS and Sensors R&D group and the University of Pavia, that led to the design of two readout circuits specifically tailored on the sensors characteristics, one for the thermopile sensor and one for the TMOS (developed by the Technion-Israel Institute of Technology), which were integrated in two test-chip prototypes and thoroughly characterized through measurements as stand-alone devices and as a system with the sensor they were designed for.
4
Ella, Samantha. « Rubber snow interface and friction ». Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/17941.
Texte intégralRésumé :
Tyres are used in everyday life for a variety of practical and recreational tasks. Frictional behaviour of tyres on any surface is important for vehicle safety and control; this behaviour becomes more important when that surface is snow. The interaction of rubber and a snow surface is complex and a deeper understanding of both is needed in order to help develop better tyres. Outdoor full scale tyre test results were compared to results from indoor laboratory tests using a linear tribometer and a surface of compacted artificial snow; these were in excellent correlation allowing a systematic and comprehensive study of rubber friction on snow to be conducted in the laboratory. Rubber samples of varied rubber compositions and geometries were used to gain an understanding of friction on snow. Samples with varying glass transition temperature (Tg), dynamic rigidity (G*) and Payne effect (dependence of the dynamic moduli on the amplitude of the applied strain) were investigated along with samples with and without sipes. The rubber friction coefficient (μ) was measured as a function of velocity and temperature. The siped samples exhibited a higher μ than those without sipes. FE simulations, rubber friction tests for varying contact pressures and steel blade force tests were performed to evaluate contributions from ‘surface’ friction and ploughing separately. The increased μ was attributed to the ploughing force from the front edges of the ‘subblocks’ created by the sipes. Although it is well known in the industry that siped tyres grip well, this is the first time it has been explained how sipes grip effectively through a combination of ploughing and rubber snow interaction. A comprehensive study of varying rubber properties (Tg, G* and Payne effect) was conducted to better understand their impact on snow friction. The findings were evaluated using the WLF shift factor to account for the running frequency of the rubber from the snow surface roughness. G* was found to be the dominant parameter for rubber μ when considering running frequency. Increased μ values were exhibited by rubbers with a lower G*. The decreased G* makes the rubber more compliant, thus increasing the contact area between the rubber and the snow, in turn increasing μ. A better knowledge of the surface roughness of snow will aid the understanding of the interaction between rubber and snow for tyres. A method was developed to characterise the artificial snow surface utilising sectioning and imaging of chemically stabilised snow samples. From images of the snow surface before friction testing the average indentor size can be found, this is used to analyse the running frequency of the rubber. Qualitatively comparing the surfaces before and after rubber friction testing shows a decrease in surface profile aggressivity after a test; this is attributed to melting of the snow from frictional heating and snow grain fracture. Friction tests were conducted to directly compare rubber friction on snow and ice using round edged samples. Again it was found that the rubber with the decreased G* exhibited higher friction; this was seen on both snow and ice confirming G* as the dominant rubber property for both surfaces, regardless of the surface roughness change. It was found that at low temperatures ice had a higher μ than snow, while at high temperatures snow exhibited a higher μ than ice. It is hypothesised that this intriguing switch is due to the surface roughness change leading to differing contact areas both with and without melt water. This switch is not seen when a simple heat transfer model is used, confirming the effect as a surface roughness change. The use of a modified Hertz model shows that indentation is the dominant mechanism at low velocities on snow. It is hypothesised that at high velocities melt water dominates on both snow and ice while adhesion may have a more significant role on ice at low velocities. These findings provide knowledge that can be used in the design of tyres for snow and ice in the future.
5
Amoah-Kusi, Christian. « Constant Interface Temperature Reliability Assessment Method : An Alternative Method for Testing Thermal Interface Material in Products ». PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2295.
Texte intégralRésumé :
As electronic packages and their thermal solutions become more complex the reliability margins in the thermal solutions diminish and become less tolerant to errors in reliability predictions. The current method of thermally stress testing thermal solutions can be over or under predicting end of life thermal performance. Benefits of accurate testing and modeling are improved silicon yield in manufacturing, improved performance, lower cost thermal solutions, and shortened test times.
The current method of thermally stress testing is to place the entire unit in an elevated isothermal temperature and periodically measure thermal performance. Isothermally aging is not an accurate representation of how the unit will be used by the customer and does not capture the thermal gradients and mechanical stresses due to different coefficients of thermal expansion of the materials used in the thermal solution.
A new testing system, CITRAM which is an acronym for Constant Interface Temperature Reliability Method, has been developed that uses an electronic test board. The approach captures the thermal and mechanical stresses accurately and improves test time by 20-30% as a result of automation. Through this study a difference in the two methods has been identified and the new CITRAM method should be adopted as current practice.
6
Le, Poul Nicolas. « Charge transfer at the high-temperature superconductor/liquid electrolyte interface ». Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391279.
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7
Narayanaswamy, Anand Subramanian. « A Non-Contact Sensor Interface for High-Temperature, MEMS Capacitive Sensors ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=case1275675071.
Texte intégral
8
Solak, Nuri. « Interface stability in solid oxide fuel cells for intermediate temperature applications ». [S.l. : s.n.], 2007. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-31048.
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9
MOURA, VICTOR NOCRATO. « Ginzbutrg-Landau theory with hidden order parameter applied to interface superconductivity ». Universidade Federal do CearÃ, 2017. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=19046.
Texte intégralRésumé :
Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgicoIn recent years, several experiments have been reported in which interface superconductivity was observed in heterostructures of different materials, inclunding non-superconductors. The origin of this superconductivity has not yet been elucidated and there is no well-established theory to explain this phenomenon. In 2015 a model based on the Ginzburg-Landau theory was proposed that would explain the interface superconductivity phenomenon assuming a system with two order parameters. It has been proposed that the order parameter characterizing the bulk material with a defective or doped layer permits the formation of a second parameter which competes with the former and prevails over it in the vicinity of the interface. The superconductivity at the interface is then explained by the growth of this second order parameter only in this region, remaining still ``hidden" inside the bulk. The model was applied to a one-dimensional system with an interface, which presented a surprising result: the ``hidden" superconductivity appers in quantized critical temperatures, this allowing the existence of several eigenstates of the system, with different critical temperatures. In this dissertation, we use this model and investigate the unfolding of hidden superconductivity and its quantized temperatures. We observe that the interfaces resemble one-dimensional quantum wells, with the critical temperature playing the role of the energy in the quantum case. Following this idea we use numerical methods to solve the Ginzburg-Landau equations for a system with an arbitrary number of parallel interfaces. Our results show that in this case, the critical temperatures are quantized and degenerate when the interfaces are very separated, but it has its degeneracy broken when we approach the interfaces, as it happens in a lattice of square wells. We then proposed a tight-binding model to estimate critical temperatures on parallel interfaces and verified the validity of this approximation through the numerical solution of the complete problem. We also analyze the vortex states for a square two-dimensional defect, verifying the possibility of creating or destroying vortices in the region of `` hidden" superconductivity through an external magnetic field.
Nos Ãltimos anos foram reportados diversos experimentos em que a supercondutividade de interface foi observada em heteroestruturas de diferentes materiais, inclusive em nÃo-supercondutores extit{a priori}. A origem dessa supercondutividade ainda nÃo foi elucidada e nÃo existe uma teoria bem estabelecida para explicar esse fenÃmeno. Em 2015 foi proposto um modelo com base na teoria de Ginzburg-Landau que explicaria o fenÃmeno de supercondutividade de interface assumindo um sistema com dois parÃmetros de ordem. Foi proposto que o parÃmetro de ordem que caracteriza o material extit{bulk} com uma camada defeituosa, ou dopada, permite a formaÃÃo de um segundo parÃmetro que compete com o primeiro e prevalece sobre ele nas proximidades da interface. A supercondutividade na interface à entÃo explicada pelo crescimento deste segundo parÃmetro de ordem apenas nesta regiÃo, permancecendo ainda ``escondido" dentro do extit{bulk}. O modelo foi aplicado para um sistema unidimensional com uma interface, apresentando um resultado surpreendente: a supercondutividade escondida aparece em temperaturas crÃticas quantizadas, podendo entÃo existir vÃrios autoestados do sistema, com diferentes temperaturas crÃticas. Nessa dissertaÃÃo utilizamos esse modelo e investigamos os desdobramentos da supercondutividade escondida e suas temperaturas quantizadas. Percebemos que as interfaces assemelham-se com poÃos quÃnticos unidimensionais, com a temperatura crÃtica fazendo o anÃlogo ao da energia no caso quÃntico. Seguindo essa ideia utilizamos mÃtodos numÃricos para resolver as equaÃÃes de Ginzburg-Landau para um sistema com um nÃmero arbitrÃrio de interface paralelas. Nossos resultados mostram que neste caso, as temperaturas crÃticas, alÃm de quantizadas, sÃo degeneradas quando as interfaces estÃo muito separadas, mas tem essa degenerescÃncia quebrada quando aproximamos as interfaces, como ocorre em uma rede de poÃos quadrados. Propusemos entÃo um modelo tipo extit{tight-binding} para estimar temperaturas crÃticas em interfaces paralelas e verificamos a validade dessa aproximaÃÃo atravÃs da soluÃÃo numÃrica do problema completo. Analisamos tambÃm os estados de vÃrtices para um defeito bidimensional quadrado, verificando a possibilidade de se criar ou destruir vÃrtices na regiÃo de supercondutividade escondida atravÃs de um campo magnÃtico externo.
10
Paruchuri, Bhavya. « Effects of Freezing Temperature on Interface Shear Strength of Landfill Geosynthetic Liner ». University of Toledo / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1321651367.
Texte intégral
11
Yu, Zhou. « Surface Polymerization, Interface Structure, and Low Temperature Consolidation of Nano Ceramic Particles ». University of Cincinnati / OhioLINK, 2000. http://rave.ohiolink.edu/etdc/view?acc_num=ucin971379308.
Texte intégral
12
Vilorio, Carlos R. « Gas Chromatography Micro-Chip with High Temperature Interface and Silk Screen Heaters ». BYU ScholarsArchive, 2020. https://scholarsarchive.byu.edu/etd/8690.
Texte intégralRésumé :
There has been substantial market demand for a portable Gas Chromatography (GC) system. Throughout the years, much progress has been made on fabricating a micro system that works as well as a benchtop system. Unfortunately, even though many substrates, channel types, channel widths, temperature control systems, and interface solutions have been attempted, existing versions of the micro-GC still fall short of the ideal. This thesis presents the design, fabrication, and testing of a silicon based micro-GC column that presents a solution for interfacing and heating of the chip. A polyimide resin is used to create a durable high temperature low thermal mass interface with the chip, while a silk screen method is demonstrated for easy printing of heaters. Chromatogram results are shown in both Temperature Program and Thermal Gradient runs.
13
Reddy, Chandra M. « Improved corrosion protection of aluminum alloys by low temperature plasma interface engineering / ». free to MU campus, to others for purchase, 1998. http://wwwlib.umi.com/cr/mo/fullcit?p9924918.
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14
Park, Jong-Jin. « Design of a new arrayed temperature sensor system and thermal interface materials / ». Thesis, Connect to this title online ; UW restricted, 2004. http://hdl.handle.net/1773/7062.
Texte intégral
15
Ishimatsu, Ryoichi. « Electrocapillarity at the interface between the room-temperature ionic liquid and water ». 京都大学 (Kyoto University), 2008. http://hdl.handle.net/2433/136305.
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16
Captain, Janine Elizabeth. « Non-thermal Interactions on Low Temperature Ice and Aqueous Interfaces ». Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/6995.
Texte intégralRésumé :
Electron-impact ionization of low-temperature water ice leads to H+, H2+,
and H+(H2O)n=1-8 desorption. The threshold energy for ESD of H2+ from CI and H3O+ from PASW and ASW is 22 ± 3 eV. There is also a H2+ yield increase at 40 ± 3 eV and a 70 ± 3 eV threshold for ESD of H+(H2O)n=2-8
from PASW and ASW. H2+
production and desorption involves direct molecular elimination and reactive
scattering of an energetic proton. Both
of these channels likely involve localized two-hole one-electron and/or
two-hole final states containing 4a1, 3a1 and/or 2a1
character. The 70 eV
cluster ion threshold implicates either an initial (2a1-2)
state localized on a monomer or the presence of at least two neighboring water
molecules each containing a single hole.
The resulting correlated two-hole or two-hole, one-electron
configurations are localized within a complex and result in an intermolecular
Coulomb repulsion and cluster ion ejection.
The changes in the yields with
phase and temperature are associated with structural and physical changes in
the adsorbed water and longer lifetimes of excited state configurations
containing a1 character. The dependence
of the ESD cation yields on the local potential has
been utilized to examine the details of HCl
interactions on low temperature ice surfaces.
The addition of HCl increases cluster ion
yields from pure ice while decreasing H+ and H2+
yields. These changes reflect the
changes in the local electronic potential due to the changing bond lengths at
the surface of the ice as HCl ionizes and the
surrounding water molecules reorient to solvate the ions.
This work has been extended to
ionic solutions at higher temperatures using a liquid jet and ultraviolet
photoionization to interrogate the surface of aqueous ionic
interfaces. Desorption of protonated
water clusters and solvated sodium ion clusters were measured over a range of
concentrations from NaCl, NaBr,
and NaI solutions.
The flux dependence indicated a multiple photon process and the proposed
mechanism involves a Coulomb explosion resulting from the repulsion of nearby
ions. The surface is investigated with
regard to its importance in heterogeneous atmospheric chemistry.
17
Addepalli, Swarnagowri. « High-Temperature Corrosion of Aluminum Alloys : Oxide-Alloy Interactions and Sulfur Interface Chemistry ». Thesis, University of North Texas, 2000. https://digital.library.unt.edu/ark:/67531/metadc2739/.
Texte intégralRésumé :
The spallation of aluminum, chromium, and iron oxide scales is a chronic problem that critically impacts technological applications like aerospace, power plant operation, catalysis, petrochemical industry, and the fabrication of composite materials. The presence of interfacial impurities, mainly sulfur, has been reported to accelerate spallation, thereby promoting the high-temperature corrosion of metals and alloys. The precise mechanism for sulfur-induced destruction of oxides, however, is ambiguous. The objective of the present research is to elucidate the microscopic mechanism for the high-temperature corrosion of aluminum alloys in the presence of sulfur. Auger electron spectroscopy (AES), low energy electron diffraction (LEED), and scanning tunneling microscopy (STM) studies were conducted under ultrahigh vacuum (UHV) conditions on oxidized sulfur-free and sulfur-modified Al/Fe and Ni3Al(111). Evaporative deposition of aluminum onto a sulfur-covered iron surface results in the insertion of aluminum between the sulfur adlayer and the substrate, producing an Fe-Al-S interface. Aluminum oxidation at 300 K is retarded in the presence of sulfur. Oxide destabilization, and the formation of metallic aluminum are observed at temperatures > 600 K when sulfur is located at the Al2O3-Fe interface, while the sulfur-free interface is stable up to 900 K. In contrast, the thermal stability (up to at least 1100 K) of the Al2O3 formed on an Ni3Al(111) surface is unaffected by sulfur. Sulfur remains at the oxide-Ni3Al(111) interface after oxidation at 300 K. During annealing, aluminum segregation to the g ¢ -Al2O3-Ni3Al(111) interface occurs, coincident with the removal of sulfur from the interfacial region. A comparison of the results observed for the Al2O3/Fe and Al2O3/Ni3Al systems indicates that the high-temperature stability of Al2O3 films on aluminum alloys is connected with the concentration of aluminum in the alloy.
18
Mačionis, Nerijus. « Protingas namas. Temperatūros stebėjimo sistema ». Master's thesis, Lithuanian Academic Libraries Network (LABT), 2008. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2008~D_20080716_105816-80833.
Texte intégralRésumé :
Ekonomiškai temperatūrą valdanti sistema turi tiekti šilumą ten kur tuo metu ji yra reikalingiausia ir minimaliai sumažinti ją ten kur ji nėra reikalinga. Tačiau bet kuriai temperatūros valdymo sistemai, tam, kad ji optimaliai valdytų temperatūrą reikalinga žinoti kokia temperatūra yra realiu laiku strategiškai svarbiuose patalpos taškuose. Našus ir greitas temperatūrinės informacijos surinkimas iš įvairių patalpų yra svarbus dalykas ne tiktai šildymo, vėdinimo, kondicionavimo procesams, bet taip pat gali būti naudojama kaip apsauga nuo gaisro. Tačiau iškyla problema – kaipgi stebėti visas temperatūras realiu laiku ir vienoje vietoje? Taigi pagrindinis darbo tikslas yra sukurti temperatūros stebėjimo sistemą, kuri yra sudaryta iš techninės ir programinės įrangos, būtų lengvai įdiegiama ir pritaikoma įvairioms patalpomis arba technologiniams procesams. Ši systema bus paprasta ir nebrangi, tačiau funkcionalumu nenusileis sudėtingoms programoms. Šiame darbe buvo išanalizuota jau egzistuojanti temperatūros stebėjimo sistemų programinė įranga, pabrėžiant jos privalumus ir tr��kumus. Atsižvelgiant į analizės rezultatus, buvo sukurta temperatūros stebėjimo sistemos projektas.Smart house system, which economically controls temperature, has to supply heating where it necessary at this time and reduce to minimum where it is not necessary. To control temperature optimally, every temperature control system has to know what temperature is in the real time at strategically important room places. Efficient and fast collection of temperature information from various house places is a matter of substance not even in processes of heating, ventilation and air conditioning but also can be used as a preventive mean from fire. But there is a main problem – how to know and observe all temperatures in real time, in one place? So the main aim of research is to design temperature monitoring system, which consists of hardware and software, would be easy installation, adapted for various accommodations or technological processes. This system would be simple and cheap, with it’s functionality would be equal with another sophisticated systems. It was analyzing properly existing temperature monitoring systems’ software at this work and marked its’ merits and demerits. It was created temperature monitoring system project.
19
Chandrasekaran, Arvind. « Effect of encapsulant on high-temperature reliability of the gold wirebond-aluminum bondpad interface ». College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/281.
Texte intégralRésumé :
Thesis (M.S.) -- University of Maryland, College Park, 2003.Thesis research directed by: Dept. of Mechanical Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
20
Tan, Feng. « Development of subroutine library and data transfer interface for high temperature structural integrity-creep ». Thesis, University of Huddersfield, 2015. http://eprints.hud.ac.uk/id/eprint/26220/.
Texte intégralRésumé :
Creep plays a critical role in the research of high temperature materials because it is the major failure form of high temperature devices. In the safety assessment of high temperature devices, creep failure is one of the key factors used to evaluate residual lifetime of metal components; however, creep analysis in practical applications is still a great challenge due to the lack of a unified theory of all materials. A number of researchers are conducting research into creep constitutive model based on either experimental approaches or computational approaches, but multifarious computational tools were used because the constitutive model is still in the exploration stage. Traditional commercial software could reach the required capability based on the development of user-developed codes; moreover, some in-house codes were proposed, but just used in a narrow scope. Therefore, the development of a novel universal creep finite element software needs to be carried out to meet the requirements of future research. This research aims to develop required subroutines and interface for the proposed elastic-creep finite element software called High Temperature Structural Integrity-Creep (HITSI). Basic concepts and situations of creep and its computational tools have been reviewed. General knowledge of programming of finite element method has also been studied. A universal subroutine template of creep constitutive equations has been given to enable users to add their own equations directly. A high order and embedded numerical method called Runge-Kutta-Fehlberg (RKF) method has been applied and discussed in order to enhance the accuracy of traditional methods. A mathematical method used to improve the accuracy and efficiency of constitutive equations subroutine call normalization has been applied and discussed. Formatted input and output of purchased pre- and post-processor has been studied to develop the data transfer interface. Some auxiliary modules such as stress transformation and nodal load arrangement have been developed to satisfy the input conditions of constitutive equations subroutines and data transfer interface.
21
Wong, Anson W. C. « The holographic interface of a fractional (2+1)D topological insulator at finite temperature ». Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/50728.
Texte intégralRésumé :
Topological insulators are materials that are insulating in the bulk but conductive on the boundary. Although standard condensed matter techniques elucidate the dissipationless boundary physics of topological insulators well at weak coupling, they fail to do the same at strong coupling where exciting phenomena such as emergence and fractionalization are likely to occur. Fortunately the AdS/CFT correspondence offers an alternative perspective of the strong coupling limit in the form of a classical supergravity dual. In this thesis we realize the interface of a strongly-interacting fractional (2+1)D time-reversal invariant topological insulator at finite temperature by embedding a D5-brane with a $U(1)$ chemical potential into (AdS₅ black hole) × S⁵ supergravity. The thermodynamics of our interface are found to be considerably fermionic. Study of the interface has promising applications ranging from the design of spin channels in quantum computing, to the deeper understanding of highly-entangled systems.Science, Faculty of
Physics and Astronomy, Department of
Graduate
22
Lee, Benjamin Chi-Pui. « Temperature gradient-driven Marangoni convection of a spherical liquid-liquid interface under reduced gravity conditions ». Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0003/MQ46102.pdf.
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Solak, Nuri [Verfasser]. « Interface stability in solid oxide fuel cells for intermediate temperature applications / vorgelegt von Nuri Solak ». Stuttgart : Max-Planck-Inst. für Metallforschung, 2007. http://d-nb.info/995375429/34.
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Navale, Sanket Sunil. « Accounting for temperature and local structure in atomistic calculations of interface free energies in metals ». Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113929.
Texte intégralRésumé :
Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2017.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 175-193).
Interfaces are ubiquitous in crystalline materials and they predominantly govern the properties of metals at nanoscale. Free energy is the most significant characteristic of an interface that determines its behavior and other properties. However, interfaces have an internal structure with nanoscale features that gives the interface free energy, a location dependent variation. The interface free energy is also expected to depend on temperature, especially for entropy stabilized phases such as liquids. I present methods for calculating location-dependent energies for solid-state interfaces and temperature-dependent free energies for solid/liquid interfaces using atomistic models. I demonstrate these methods on CuNbHe and AlGa models due to the importance of location- and temperature-dependence of interface energies in these systems. My analysis sheds light on interfacial He precipitation in CuNb composites and on Ga permeation through grain boundaries (GB) in Al. Based on the Gibbsian definition of excess interface energy, I develop a method to compute location dependent energy of solid/solid interface from atomic level energies and apply it to characterize four different Cu/Nb interfaces and several GBs of Al. The solid-state interface energies are indeed location-dependent and vary at the length scale of few nanometers. For any particular interface, the variation in the energies spans a range of ś100% of its average energy. The higher energy regions correspond to the underlying misfit dislocation network of the semicoherent interfaces. I compute the stress of solid/liquid interface from capillary pressure of the interface using the Young-Laplace equation and then derive its free energy. Applying this method to Cu/He and Nb/He interfaces, I find that these interface energies are dependent on He pressure and interface curvature but not explicitly on temperature. I fit analytical expressions for these interface free energies and study the impact of their curvature dependence on He cluster growth. For instance, the incorporation of curvature dependence of metal-He interface free energies accounts for a decrease of up to 1GPa in the pressure required to punch out a dislocation from the bubble into the metal. Al/Ga interface energy is found to be negative, implying that Ga can spread on all Al surfaces and GBs. The computed interface energies may be used to predict the distribution of He precipitates at CuNb interfaces while interface energies for AlGa shed light on the crystallographic character-dependence of Ga permeation through Al GBs. These results may be directly incorporated into phase field models of He behavior in CuNb composites and Ga behavior at Al GBs.
by Sanket Sunil Navale.
Ph. D.
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Lotse, Henrik. « Electrical analysis of interface recombination of thin-film CIGS solar cells ». Thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-426324.
Texte intégralRésumé :
In this master thesis, electrical characterization of thin film CuInxGa(1−x)Se2 solar cells produced by Midsummer AB were performed with the aim of determining the dominant recombination path of these cells. Current-Voltage (IV), Quantum Effinciency (QE), temperature dependent IV (IVT) and Drive-Level Capacitance Profiling (DLCP) was used with the objective to investigate the dominant recombination path as well as provide some insight of the solar cells in order to create a baseline model using the modelling software SCAPS (Solar cell CAPacitance Simulator). The IV produced mostly consistent results with slight variation, most likely due to non uniformity of equipment. The QE showed consistent results between all cells indicating a stable process for the sample preparation. Using IVT measurements were taken from a temperature of 115K −300K in order to obtain the activation energy for the dominant recombination path. By comparing it with the band gap energy from the QE measurement, it was found that the dominant recombination path is in either the space charge region or in the bulk of the CIGS and not at the hetero interface. DLCP measurement were made at both low temperature and at room temperature and revealed that the cells had a similar doping as other comparable cells at 7×1016cm−3 . The initial baseline model created in SCAPS show a good agreement with the measured IV and currently indicates a spike in the band alignment, supporting the results for the IVT measurement.
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Vasilescu, Andreea-Roxana. « Design and execution of energy piles : Validation by in-situ and laboratory experiments ». Thesis, Ecole centrale de Nantes, 2019. http://www.theses.fr/2019ECDN0015/document.
Texte intégralRésumé :
Les pieux énergétiques représentent une solution alternative intéressante, face à l’accroissement des besoins mondiaux en énergie et à la réduction de l’utilisation des énergies fossiles. L’objectif principal de la thèse est d’identifier et de quantifier les principaux facteurs influençant le dimensionnement des pieux géothermiques, qui sont impactés par les changements de température des pieux lors de leur activité. Pour ce faire, ce travail de thèse a été dressé en 3 campagnes expérimentales, dont deux à échelle réelle : (i) une première campagne à chargement thermomécanique contrôlé (Marne La Vallée), (ii) une seconde campagne en conditions d’utilisation réelles sous une station d’épuration (Sept Sorts) et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermique. et (iii) une troisième campagne à l’échelle du laboratoire grâce à une nouvelle machine de cisaillement direct d’interface permettant l’étude du comportement thermo mécanique des interfaces sol-structure. Ces trois campagnes expérimentales ont pour but de quantifier l’effet de la température et des cycles de température sur le comportement des pieux énergétiques. Les premiers résultats expérimentaux de la campagne de Sept Sorts ont ensuite été simules dans le code LAGAMINE via la méthode des éléments finis, afin d’adopter une approche complémentaire permettant de mieux appréhender la réponse thermomécanique de ce type de pieu lors de l’activation géothermiqueEnergy piles, also called thermo-active piles, are an alternative solution to the increase in the global energy demand as well as in mitigating socio-economical stakes concerning the increase of energy costs due to fossil fuels. Energy piles are double purpose structures that allow transferring the loads from the superstructure to the soil and that integrate pipe circuits allowing heat exchange between the pile and the surrounding ground. The objective of this thesis is to identify and quantify the principal parameters involved in the geotechnical design of pile foundations impacted by temperature changes associated with geothermal activation. For this purpose, this research work was organized in 3 experimental campaigns: (i) A full scale load controlled test at Ecole des Ponts Paris-Tech, (ii) Full scale energy piles monitoring under real exploitation conditions at Sept Sorts, (Seine et Marne, France), (iii) Laboratory tests in order to assess the effect of temperature and temperature cycles at the soil-pile interface. The experimental results are used to estimate the effect of geothermal activation of a pile foundation, on its bearing capacity as well as on its long-term exploitation. Finally, preliminary numerical simulations were performed using a thermo-hydro mechanical model, using the finite element method code LAGAMINE able to capture the main phenomena
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Kaminise, Almir Kazuo. « Estudo da influência do material do porta-ferramenta sobre temperaturas de usinagem no torneamento ». Universidade Federal de Uberlândia, 2012. https://repositorio.ufu.br/handle/123456789/14725.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe main objective of this work is the experimental investigation of the effect that the material of the toolholder has on the temperature at tool-chip interface and on the surface temperatures of the cutting tool and toolholder. The study was conducted in dry turning of gray iron with uncoated cemented carbide inserts, using the same cutting parameters. Five toolholders had been confectioned in materials having different thermal conductivity, these being: copper, brass, aluminum, stainless steel and titanium alloy. The toolholders are identical and have the constructive aspects obtained from a commercial toolholder for turning that material. The temperature at the tool-chip interface was measured using the toolworkpiece thermocouple method and the surface temperatures in the tools and the toolholders, by conventional type T thermocouples. The system was modified in order to develop an experimental procedure for the physical compensating of the secondary and parasites thermoelectric signals (emf). Also, modifications was carried out in a conventional tailstock for use in driving the emf signal between the workpiece and a stationary conductor, but without significantly altering the stiffness of the system. The tailstock was electric insulated and a mercury bearing was mounted inside it and their internal connections were turned in reference junctions at room temperature because on otherwise it could act as secondary junctions. The calibration of the tool-workpiece thermocouple was developed in the same experimental apparatus using the modifications implemented in this system. Besides the results obtained with the investigation of the effects of the toolholder material on the surface temperatures of the tool and the tool holder and on the tool-chip interface temperature, this research also presents contributions to the use and performance of the tool-workpiece thermocouple method.
O objetivo principal deste trabalho é a investigação experimental do efeito que o material do porta-ferramenta exerce sobre a temperatura na interface ferramenta/cavaco e sobre as temperaturas superficiais da ferramenta de corte e do próprio porta-ferramenta. O estudo foi desenvolvido com a operação de torneamento cilíndrico externo de ferro fundido cinzento, a seco, com insertos de metal duro, em parâmetros de corte fixos. Cinco portas-ferramentas foram confeccionados em materiais com condutividades térmicas diferentes, sendo esses: cobre, latão, alumínio, aço inoxidável e liga de titânio. Os portas-ferramentas são geometricamente idênticos e têm as características construtivas de um porta-ferramenta comercial próprio ao torneamento daquele material. Mediu-se a temperatura na interface ferramenta/cavaco usando o método do termopar ferramenta-peça e as temperaturas superficiais na ferramenta e nos suportes, por meio de termopares convencionais do tipo T. O sistema termopar ferramenta-peça foi modificado no sentido de se desenvolver um procedimento experimental para a compensação física de forças eletromotrizes secundárias e parasitas. Destaca-se a execução de modificações em uma contra ponta rotativa convencional para o seu uso na condução do sinal da força eletromotriz entre a peça e um condutor estacionário sem, contudo, alterar significativamente a sua rigidez na fixação da peça. Nessas modificações, aplicou-se uma isolação elétrica permanente, implantou-se um mancal de mercúrio no seu interior e promoveu-se mudanças nas suas conexões internas, que poderiam agir como junções secundárias, transformando-as em junções de referência à temperatura ambiente. A calibração do sistema termopar ferramenta-peça foi desenvolvida sobre o próprio aparato experimental usando as modificações implantadas nesse sistema. Os resultados obtidos no trabalho mostram que os materiais usados nos suportes influenciam nas temperaturas superficiais da ferramenta e do porta-ferramenta, porém, que tais materiais não tem efeito significativo sobre as temperaturas da interface ferramenta/cavaco. Além disso, o trabalho apresenta, também, contribuições ao uso e calibração do método do termopar ferramenta-peça.
Doutor em Engenharia Mecânica
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Runge, Benjamin [Verfasser]. « X-Ray Scattering Investigations of the Temperature and Potential Dependent Structure of the Mercury-Electrolyte Interface / Benjamin Runge ». Kiel : Universitätsbibliothek Kiel, 2015. http://d-nb.info/1075756979/34.
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Tameoka, H., A. Mori, M. Tabuchi et Y. Takeda. « Influence of growth rate and temperature on InP/GaInAs interface structure analyzed by X-ray CTR scattering measurement ». IEEE, 2009. http://hdl.handle.net/2237/13941.
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Temirov, Ruslan [Verfasser]. « Studying complex metal-molecule interface with low temperature scanning tunneling microscope : from electronic structure to charge transport / Ruslan Temirov ». Bremen : IRC-Library, Information Resource Center der Jacobs University Bremen, 2008. http://d-nb.info/1034984187/34.
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Yu, Xinyu. « High-temperature Bulk CMOS Integrated Circuits for Data Acquisition ». Case Western Reserve University School of Graduate Studies / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=case1144420886.
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Nguyen, Doan Chau Yen. « Role of deposition temperature and concentration on the self-assembly and reaction of organic molecules at the solution-graphite interface ». Doctoral thesis, Universitätsbibliothek Chemnitz, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-223658.
Texte intégralRésumé :
Das Hauptthema dieser Dissertation ist die Untersuchung der Selbstorganisation organischer Moleküle an der Flüssig-Fest-Grenzfläche (LSI). Besondere Betonung liegt auf der Kontrolle der Selbstassemblierung durch geeignete Parameter: die Substrattemperatur während der Abscheidung, die Konzentration der gelösten Moleküle, und die chemische Natur der gelösten Stoffe und Lösungsmittel. Die Untersuchungen wurden unter Verwendung der Rastertunnelmikroskopie (STM) durchgeführt. Der erste Schwerpunkt dieser Arbeit ist die systematische Untersuchung der Auswirkung erhöhter Substrattemperatur während der Abscheidung aus der Lösung auf die Selbstorganisation komplexer molekularer Architekturen an der LSI. Diese Untersuchungen wurden mit dem planaren Molekül Trimesinsäure (TMA), sowie dem nicht-planaren Molekül Benzen-1,3,5-triphosphonsäure (BTP) durchgeführt. Es wird gezeigt, dass der Polymorphismus der Adsorbatstrukturen von TMA und BTP durch die Substrattemperatur während der Abscheidung der Moleküle aus der Lösung für verschiedene Lösungsmitteln unterschiedlicher Polarität, wie Phenyloctan, Octansäure und Undecanol, kontrolliert werden kann. Durch die Erhöhung der Temperatur des vorgeheiztem Graphitsubstrates kann die spezifische 2D supramolekulare Struktur and die entsprechende Packungsdichte der Moleküle in der Adsorbatschicht für jedes der untersuchten Lösungsmittel präzise eingestellt werden. Weiterhin wird der Einfluss der Konzentration auf die resultierende Anordnung der TMA Moleküle an der LSI durch ein weiteres Experiment abgeschätzt, bei welchem Rühren (von 0 h bis 40 h) der Lösungen mit verschiedenen Lösungsmitteln eingesetzt wurde. Diese Ergebnisse zeigen, dass die verschiedenen Präparationsmethoden (Erhöhung der Abscheidetemperatur oder Rühren) zu derselben Tendenz der Änderung der geordneten Strukturen sowie der Packungsdichte führt, weswegen man schlussfolgern kann, dass die Erhöhung der Konzentration an der LSI bei erhöhter Abscheidetemperatur ebenso der Hauptgrund für die beobachteten Änderungen ist. Der zweite Schwerpunkt dieser Dissertation ist die Untersuchung von chemischen Reaktionen der selbstassemblierenden Moleküle. Eine Veresterungsreaktion von TMA mit Undecanol wurde gefunden. Weiterhin wurde, als ein erster Schritt zur Untersuchung der Zwillingspolymerisation, die Oligomerisation des Zwillingsmonomers 2,2’-spirobi [4H-1,3,2-benzo-dioxasiline] (SBS) mit STM an der Grenzfläche zwischen der SBS-Undecanol-Lösung und einer Graphitoberfläche untersucht. Erstens wurde durch Ultraschallbehandlung der SBS Lösung in Undecanol für verschieden lange Zeiten die Oligomerisation der SBS Monomere ohne einen Katalysator an der LSI beobachtet. Zweitens konnte die Oligomerisation auch durch Erhöhung der Substrattemperatur während der Abscheidung der Moleküle aus der Lösung initiiert werden. Durch die schrittweise Erhöhung der Temperatur des vorgeheizten Substrates konnten mehrere, verschiedene, periodische Anordnungen von Phenol‒Dimeren, ‒Trimeren, und –Pentameren u.s.w. gefunden werden. Weiterhin wird die Auswirkung der Abscheidetemperatur auf die Selbstorganisation an der LSI nur der Lösungsmittelmoleküle aus dem reinen Lösungsmittel beschrieben. Dies ist wichtig, da die Undecanol‒Moleküle stets mit den gelösten, in dieser Arbeit verwendeten Stoffen (TMA, BTP, SBS) koadsorbieren und lineare Muster bildenThe main aim of this thesis is to study the self-assembly of organic molecules at the liquid-solid interface (LSI). Special emphasis is given to controlling the process of self-assembly via suitable parameters such as: the substrate temperature during the initial deposition, the concentration of dissolved molecules, or the chemical nature of solutes and solvents. The investigations are performed using scanning tunneling microscopy (STM). The first focus of this work is the systematic investigation of the effect of the substrate temperature during the deposition out of the solution on the self-assembly of complex molecular architectures at the LSI. These investigations have been done with the planar molecule trimesic acid (TMA), and the non-planar molecule benzene 1,3,5-triphosphonic acid (BTP). We show that the polymorphism of the adsorbate structures of TMA (also with BTP) can be controlled by the substrate temperature during the deposition of the molecules out of the solution for various solvents of different polarity such as phenyloctane, octanoic acid, and undecanol. By increasing the temperature of the pre-heated graphite substrate, the specific 2D supramolecular structure and the corresponding packing density in the adsorbate layer can be precisely tuned for each kind of the solvents studied. Furthermore, the influence of the concentration on the resulting self-assembly of TMA molecules at the LSI is estimated by another experiment using stirring (from 0 h to 40 h) of the solutions of different kinds of solvents. These results demonstrate that choosing different preparation methods (increasing deposition temperatures or stirring) lead to the same tendency in the change of the self-assembled structures as well as the tuning of the packing density from which it can also be concluded that the increase of the concentration at increased deposition temperatures is also the main reason for the observed changes. The second focus of this work is the investigation of chemical reactions of self-assembling molecules. The esterification of TMA with undecanol was observed. Moreover as a first step to study twin polymerization, the oligomerization of the twin monomer 2,2’-spirobi [4H-1,3,2-benzo-dioxasiline] (SBS) was investigated by STM at the SBS-undecanol solution/graphite interface. Firstly, by ultrasonicating the solution of SBS in undecanol for different times the oligomerization of SBS monomer without any catalyst has been observed at the LSI. Secondly, the oligomerization of SBS monomer can also be initiated by the substrate temperature during the deposition of the molecules out of the solution. By stepwise increasing the temperature of the pre-heated substrate, various periodic assemblies of phenolic dimer, trimer, pentamer resin, and so on were observed. Furthermore, the effect of deposition temperature on the self-assembly of solely solvent molecules from the pure liquid at the LSI is described, which is important because the undecanol solvent molecules are always co-adsorbed with the solutes used in this work (TMA, BTP, SBS) to form linear patterns
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Chrysovergis, Taki Stavros. « Laboratory Investigation of the Effects of Temperature and Moisture on Interface Shear Strength of Textured Geomembrane and Geosynthetic Clay Liner ». DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/899.
Texte intégralRésumé :
A laboratory investigation was conducted to determine the effects of temperature and moisture on the shear strength of textured geomembrane (T-GM) and geosynthetic clay liner (GCL) interface. Several landfill slope failures involving geosynthetics have occurred within the past three decades. Interface shear strength of T-GM/GCL is well documented for testing conducted at laboratory temperatures and at moisture contents associated with GCLs in submerged conditions. However, in-service conditions for landfill liner systems include a wide range of temperatures (extending from below 0 °C to above 40 °C) and a wide range of moisture conditions. Large-scale interface direct shear tests were performed at normal stresses of cover liners (10, 20, and 30 kPa) and bottom liners (100, 200, and 300 kPa). Cover liner specimens were subjected to temperatures of 2, 20 and 40 °C; and bottom liner specimens were subjected to temperatures of 20 and 40 °C. Both cover and bottom liner specimens were prepared at moisture contents of as-received (approx. 18-19%), 50%, and 100%.
Cover liner specimens exhibited decreased peak interface shear strength (tp) with increasing temperature. Specimens sheared at 2 °C exhibited greater tp than those sheared at 20 °C by as much as 27%. Specimens sheared at 20 °C exhibited greater tp than those sheared at 40 °C by as much as 16%. Large-displacement interface shear strength (tld) generally exhibited a bell-shaped relationship with increasing temperature with the greatest tld at 20 °C. A bell-shaped relationship was exhibited between temperature and peak and large-displacement interface friction angle (dp and dld). dp ranged from 17.4 to 26.3°, 23.8 to 29°, and 20.4 to 22.2° for 2, 20, and 40 °C, respectively. dld ranged from 12.7 to 18.2°, 18.2 to 20.6°, and 15.9 to 16.7° for 2, 20, and 40 °C, respectively. Decreased d at 2 and 40 °C were largely attributed to increased geosynthetic damage. Bottom liner specimens exhibited decreased tp and tld with increasing temperature by up to 12% and 16%, respectively. Bottom liner specimens exhibited decreased tp and tld with increasing moisture content by up to 14% and 36%, respectively. For bottom liner specimens, a trend of decreased dp with increased temperatures was exhibited. dp ranged from 20 to 24.7° and 19.5 to 22.2° for 20 °C and 40 °C, respectively. dld ranged from 10.4 to 15.6° and 8.9 to 13.9° for 20 °C and 40 °C, respectively. Decreased d at 40 °C was largely attributed to increased geosynthetic damage and increased bentonite extrusion. Increased moisture content resulted in decreased dp and dld by up to 4.7 and 5.1°, respectively. Results of this testing program indicated that T-GM/GCL interface shear strengths are influenced by temperature and moisture content within ranges representative of field conditions. Interpolation factors and reduction factors were developed for use to avoid overestimation of d when determined at standard laboratory temperatures. For cover liners, reduction factors of 0.8 and 0.85 are recommended for dp and dld, respectively. For bottom liners, reduction factors of 0.9 and 0.85 are recommended for dp and dld, respectively.
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Qin, Yangzhong. « Ultrafast Hydration Dynamics Probed by Tryptophan at Protein Surface and Protein-DNA Interface ». The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1416998263.
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Xi, Lixia. « High-temperature interactions of molten Ti-Al, Ni-Al and Ni-B alloys with TiB2 ceramic ». Doctoral thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2017. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-220946.
Texte intégralRésumé :
Untersuchungen der Hochtemperaturbenetzung und Grenzfächeninteraktionen in Flüssigmetall/Übergangsmetall-Diborid-Systemen werden durch die technologische Nachfrage nach qualitative hochwertigen Metall-Matrix-Kompositen und verläßlichen Verbindungen von Ultrahochtemperaturkeramiken für aggressive chemische und/oder thermische Umgebungen angetrieben. Die physikalischen und chemischen Charakteristika der Metall/Keramik-Grenzflächen (z.B. die Benetzungskinetik, Grenzflächenreaktionen und die Phasenbildung) sind unerläßlich um die fundamentalen Mechanismen, die kontrollierenden technologischen Parameter, sowie die definierenden Eigenschaften und die Qualität des Endprodukts zu verstehen. Die Methode des liegenden Tropfens (engl. sessile drop method) ist die am häufigsten verwendete Verfahren für die quantitative Charakterisierung der Benetzungseigenschaften und für die direkte Untersuchung von Grenzflächeninteraktionen zwischen Flüssigmetall und festen Substraten unter Zuhilfenahme von Mikroskopie. Der Fokus dieser Arbeit liegt auf der Hochtemperaturbenetzung und den Grenzflächeninteraktionen von geschmolzenen reinem Al und Ti-Al, Ni-Al und Ni-B Schmelzen mit der TiB2 Ultrahochtemperaturkeramik. Die über die Methode des liegenden Tropfens hergestellten Metall/Keramik Verbunde werden hauptsächlich mittels Rasterelektronenmikroskopie gekoppelt mit energiedispersiver Röntgenspektroskopie sowie Röntgenbeugung untersucht. Die temperatur- und zeitabhängige Benetzung von flüssigem Al auf der TiB2 Keramik wurde mittels der klassischen Technik des liegenden Tropfens und der sogenannten dispensed drop technique (engl.) über einen weiten Temperaturbereich untersucht. Die Ergebnisse zeigen, dass mit ansteigender Temperatur die Benetzung bedeutend schneller abläuft. Die beiden Methoden liefern einen Unterschied in der Benetzungstemperatur von etwa 300°C aufgrund der nativen Oxidschicht auf der Al-Oberfläche bei dem klassischen Sessile-drop Versuch. Beginnend bei 1000°C füllt das flüssige Al entweder die intergranularen Poren auf oder dringt entlang der Korngrenzen in das TiB2 Substrat ein. Es wurde keine Reaktion im Al/TiB2 System beobachtet. Die Grenzflächeninteraktionen zwischen Ti-Al Schmelzen und der TiB2 Keramik wurden mit der klassischen Technik des liegenden Tropfens untersucht, da ein passender Tiegel für flüssiges Ti und Ti-haltige Schmelzen nicht vorhanden war. Für reines Ti auf TiB2 setzt das Schmelzen bei etwa 120 °C unter seinem Schmelzpunkt ein, wie aus Untersuchungen der Form und Struktur der erstarrten Ti/TiB2 Proben hervorgeht. Dies wird durch Festkörperdiffusion von B aus dem Substrat in die Ti Probe hinein und einer Verschiebung der Zusammensetzung von reinem Ti zu einer Ti-B Legierung in der substratnahen Region verursacht. Die Rolle von Al scheint für das Eindringen von Ti-Al Schmelzen entlang von Krongrenzen in das Keramiksubstrat von größerer Bedeutung zu sein als die Rolle der Temperatur. Die Benetzung und Grenzflächeninteraktionen zwischen Ni-Al Schmelzen und TiB2 wurden mit dem dispensed drop Verfahren untersucht. Flüssige Ni-Al Legierungen zeigen deutlich unterschiedliche Benetzungsverhalten auf dem TiB2 Substrat in Abhängigkeit von Legierungszusammensetzung und Testbedingungen. Das Verhalten von Ni-Al Schmelzen auf TiB2 Keramik verändert sich von einem auflösenden, reaktiven Benetzen (engl. dissolutive, reactive wetting) auf der Ni-reichen Seite zu einem nicht-reaktiven Benetzen auf der Al-reichen Seite. Die Ergebnisse deuten darauf hin, dass der Ni-Gehalt in Ni-Al Legierungen eine Hauptursache für die Veränderungen der Substratauflösung und der geometrischen Konfiguration an der Metall/Keramik Grenzfläche ist. Um den Einfluss des Ni-Gehalts auf die Auflösung von TiB2 zu verstehen wurde das Schmelzen und Benetzen von Ni83B17 und Ni50B50 Legierungen auf der TiB2 Keramik mittels der klassischen Technik des liegenden Tropfens im Hinblick auf mögliches fügen von TiB2 Keramiken untersucht. Basierend auf den Benetzungstest wurden Zwischenschichten der Ni50B50 Legierung verwendet um TiB2 Keramiken zu Verbinden. In dieser Arbeit wurde die Technik des liegenden Tropfens erfolgreich angewandt um die Hochtemperaturbenetzung und die Grenzflächeninteraktionen zwischen flüssigen Al, Ti-Al, Ni-Al und Ni-B Legierungen und keramischem TiB2 zu untersuchen. Die in dieser Arbeit erhaltenen Ergebnisse ermöglichen ein besseres Verständis der Interaktionsmechanismen zwischen flüssigen Al, Ti-Al, Ni-Al und Ni-B Legierungen und TiB2 keramik in diesen Systemen ermöglichen und Erstellung von Richtlinien für die Herstellung von Metall-Matrix-Verbunden und/oder Keramik-Matrix-Verbunden sowie für die Verbindung von keramischen TiB2 Teilen für strukturelle Hochtemperaturanwendungen darInvestigations of high-temperature wetting and interfacial interactions in liquid metal/transition-metal diboride systems are driven by technological demand in obtaining high-quality metal matrix composites and reliable joining of ultrahigh-temperature ceramics for aggressive chemical and/or thermal environments. The physical and chemical characteristics of metal/ceramic interface (e.g. wetting kinetics, interfacial reactions and phase formation) are indispensable for understanding the fundamental mechanisms, controlling technological parameters, and defining the properties and quality of final products. The sessile drop method is the most commonly used for quantitative characterization of the wetting properties and direct investigations of the interfacial interactions between a liquid metal and a solid substrate with the help of microscopy. This thesis is focused on the high-temperature wetting and interfacial interactions of molten pure Al and Ti-Al, Ni-Al and Ni-B alloys with TiB2 ultra-high-temperature ceramic. The metal/ceramic couples after the sessile drop tests are mainly characterized using scanning electron microscopy coupled with energy dispersive X-ray spectroscopy and X-ray diffraction. The temperature- and time-dependent wetting between the liquid Al and TiB2 ceramic over a wide temperature range was investigated using the classical sessile drop and dispensed drop techniques. The results showed that the wetting was significantly accelerated with increasing temperature. A difference of the wetting temperature by these two techniques was about 300 °C, due to the native oxide film present on the Al surface in the classical sessile drop tests. Starting from 1000 °C, liquid Al either filled the inter-grain pores or penetrated along the grain boundaries of the TiB2 substrate but there was no reaction observed in the Al/TiB2 system. The interfacial interactions between Ti-Al melts and TiB2 ceramic were studied by the classical sessile drop technique due to the absence of appropriate crucible for liquid Ti and Ti-containing melts. Pure Ti on TiB2 exhibited an incipient melting at about 120 °C below its melting point in view of the shape and structure of the solidified Ti/TiB2 couple. It was caused by the solid state diffusion of boron from the substrate into the Ti sample and a composition shift from pure Ti to a Ti-B alloy in the near-substrate region. In comparison to pure Ti, the role of Al in the penetration of Ti-Al melts penetration along the grain boundaries in the ceramic seemed to be more important than that of temperature in this study. The wetting and interfacial interactions between Ni-Al molten alloys and TiB2 were investigated using the dispensed drop technique. Liquid Ni-Al alloys showed a strong dependence of the wetting behavior on the TiB2 substrates, both on the alloy composition and testing conditions. It changed from a dissolutive, reactive wetting on the Ni-rich side to a non-reactive wetting on the Al-rich side. The results suggest that Ni content in Ni-Al alloys plays a major role in the changes of substrate dissolution and geometrical configuration at the metal/ceramic interface. To understand the effect of the Ni content on TiB2 dissolution, the melting and wetting of Ni83B17 and Ni50B50 alloys on TiB2 ceramic were investigated using the classical sessile drop technique in view of possible joining of TiB2 ceramics. Based on the wetting tests, TiB2 ceramics have been joined using Ni50B50 melt-spun ribbon as an interlayer. The results obtained in this work provide a better understanding of the interaction mechanisms in between liquid Al, Ti-Al, Ni-Al and Ni-B alloys and TiB2 ceramic and make basis for development of guidelines for the preparation of metal matrix composites and/or ceramic matrix composites and joining of TiB2 ceramic parts for high-temperature structural applications
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Inman, Ian A. « Compacted oxide layer formation under conditions of limited debris retention at the wear interface during high temperature sliding wear of superalloys ». Thesis, Northumbria University, 2004. http://nrl.northumbria.ac.uk/688/.
Texte intégralRésumé :
For many applications, including power generation, aerospace and the automobile industry, high temperature wear provides serious difficulties where two or more surfaces are able to move relative to one another. It is increasingly the case that with for example, aerospace applications, demands for ever more powerful and efficient engines that thus operate at higher temperatures, conventional lubrication is no longer sufficient to prevent direct contact between metallic surfaces and consequent accelerated wear. One phenomenon that has been observed to reduce metallic contact and thus high temperature wear and friction is the formation of what are termed ‘glazes’, essentially layers of compacted oxide wear debris that becomes sintered together to form a low friction wear resistant oxide surface. This thesis studies the nature of the wear encountered with four different combinations of Superalloys, slid together using a ‘block-on-cylinder’ configuration developed for accelerated simulation testing of car engine ‘valve-on-valve-seat’ wear. Predominantly, Nimonic 80A and Incoloy MA956 were used as sample materials and Stellite 6 and Incoloy 800HT were used as counterface materials.
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Depoid, Christophe. « Couplage entre paroi semi-transparente et cavites d'air par conduction, convection et rayonnements : mesure des temperatures d'interface ». Paris 6, 1988. http://www.theses.fr/1988PA066193.
Texte intégralRésumé :
Le probleme etudie est celui des mesures de temperature a la surface de parois semi-transparentes: les capteurs utilises (thermocouples colles) introduisent des perturbations qui, dans le cas ou le niveau d'echange est bas, tel que celui de l'habitat, peuvent etre du meme ordre que les effets etudies. Ce travail, mene simultanement sur le plan experimental et numerique par calage de modeles, concerne donc la mesure de temperature de surface, ainsi que l'evaluation et l'interpretation des perturbations creees par les capteurs utilises. La methodologie repose sur l'analyse de situations caracterisees par des conditions aux limites en surface de complexite croissante: conduction et rayonnement infra-rouge, convection naturelle, puis rayonnement visible
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Singh, Hitendra Kumar. « Determining Interfacial Adhesion Performance and Reliability for Microelectronics Applications Using a Wedge Test Method ». Thesis, Virginia Tech, 2004. http://hdl.handle.net/10919/30973.
Texte intégralRésumé :
Fracture mechanics is an effective approach for characterizing material resistance to interfacial failure and for making interface reliability predictions. Because interfacial bond integrity is a major concern for performance and reliability, the need to evaluate the fracture and delamination resistance of an interface under different environmental conditions is very important. This study investigates the effects of temperature, solution chemistry and environmental preconditioning, in several solutions on the durability of silicon/epoxy and glass/epoxy systems. A series of experiments was conducted using wedge test specimens to investigate the adhesion performance of the systems subjected to a range of environmental conditions. Both silicon and glass systems were relatively insensitive to temperature over a range of 22-60°C, but strongly accelerated by temperatures above 60°C, depending on the environmental chemistry and nature of the adhesive system used.
Silicon/commercial epoxy specimens were subjected to preconditioning in deionized (DI) water and more aggressive solution mixtures prior to wedge insertion to study the effect of prior environmental exposure time on the system. The wedge test data from preconditioned specimens were compared with standard wedge test results and the system was insensitive to preconditioning in DI water but was affected significantly by preconditioning in aggressive environments. Plots describing - G (crack velocity versus applied strain energy release rate) characteristics for a particular set of environmental conditions are presented and a comparison is made for different environmental conditions to quantify the subcritical debonding behavior of systems studied. A kinetic model to characterize subcritical debonding of adhesives for microelectronic applications is also proposed based on molecular interactions between epoxy and a silane coupling agent at the interface and linear elastic fracture mechanics, which could help predict long-term deterioration of interfacial adhesion.Master of Science
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Krist, Michael S. « The Design and Manufacture of a Light Emitting Diode Package for General Lighting ». DigitalCommons@CalPoly, 2010. https://digitalcommons.calpoly.edu/theses/255.
Texte intégralRésumé :
Lighting technologies have evolved over the years to become higher quality, more efficient sources of light. LEDs are poised to become the market standard for general lighting because they are the most power efficient form of lighting and do not contain hazardous materials. Unfortunately, LEDs pose unique problems because advanced thermal management is required to remove the high heat fluxes generated by such relatively small devices. These problems have already been overcome with complex packaging and exotic materials, but high costs are preventing this technology from displacing current lighting technologies.
The purpose of this study is to develop a low-cost LED lighting package capable of successfully managing heat. Several designs were created and analyzed based on cost, thermal performance, ease of manufacturing, and reliability. A unique design was created which meet these requirements. This design was eventually assembled as a prototype and initial testing was conducted. This thesis reviews the design process and eventual results of the LED package design.
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Majerčík, Miloš. « Ovládání periférií webovým rozhraním systému s 8 bit. mikroprocesorem ». Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-217720.
Texte intégralRésumé :
This diploma thesis deals with description and subsequent implementation of web interface and control device for selected periphery devices through the use of processor module RabbitCore RCM3700 which is based on microprocessor Rabbit 3000. The importance of web interface based control is currently raised because of higher customers’ claims. Interactivity of these devices contains wide range of services, from simple event communication by text messages to complex driving systems for home which create the base of intelligent house. The customer can choose either the complete and more expensive solution or self-created one. There are two possible ways of creation. The first way is through the use of personal computer. The second one, more complex but also more effective, is by single-chip microprocessor. In this thesis the second one way is used. The module with processor with build-in web interface was used. Description and the way of control are given for this module and also for selected periphery devices, the LCD and digital temperature sensors. At the end the hardware and software part of control device is designed on the basis of gained information. The thesis contains also its brief description.
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CORREA, PAULO R. « Desenvolvimento de uma interface de comunicação para determinação da difusividade térmica em função da temperatura, por termografia no infravermelho ». reponame:Repositório Institucional do IPEN, 2013. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10504.
Texte intégralRésumé :
Made available in DSpace on 2014-10-09T12:41:14Z (GMT). No. of bitstreams: 0Made available in DSpace on 2014-10-09T14:08:34Z (GMT). No. of bitstreams: 0
Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
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Yoon, Junro. « A Study of Interface Reaction of Li0.35La0.55TiO3-Li2CO3 and Its Effect on Potentiometric CO2 Gas Sensors ». The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354666091.
Texte intégral
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Alemani, Mattia. « Particle emissions from car brakes : The influence of contact conditions on the pad-to-rotor interface ». Doctoral thesis, KTH, Tribologi, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208701.
Texte intégralRésumé :
Due to their adverse health effects emissions have been regulated for over three decades. Brake wear particulate matter is the most important non-exhaust source, however current knowledge is mainly limited to observational studies. This thesis aims to investigate relations between the brake system contact conditions and the related emissions on a model scale; validate the results on a component level; and understand to what extent they are significant on a full-scale. Paper A investigates the influence of nominal contact pressure on a model scale. Results show that higher pressure corresponds to higher emissions Paper B investigates the influence of the nominal contact pressure, for different friction materials, on a model scale. A temperature threshold, responsible for a relevant emission increase, is identified. Paper C investigates particle characteristics and wear mechanisms for different nominal contact pressures, on a model scale. Results show an enhanced tribo-layer at higher pressure levels. Paper D investigates the influence of brake system conditions on emissions, on a model scale. Results show that frictional power is the most important parameter. A transition temperature independent of the contact condition is identified. Paper E investigates similarities occurring on a component scale and a model scale in terms of emissions. Results show a promising correlation, and the possibility of using a pin-on-disc tribometer for R&D activities. Paper F investigates analogies occurring on a component scale and a model scale, in terms of friction performance, fictional surface and chemical composition. Results show similar phenomena occurring for the two test stands. Paper G analyses real brake system working conditions in a urban environment defining, by means of an inertia dyno bench, the related emissions. Results reveal emission factors compliant to EURO6 and EURO2 regulations, in terms of number and mass, respectively.På grund av deras negativa hälsoeffekter har partikel emissioner reglerats i över tre årtionden. Bromsslitagepartiklar är den viktigaste icke-avgaskällan, men nuvarande kunskaper är huvudsakligen begränsade till observationsstudier. Avhandlingen syftar till att undersöka förhållandena mellan bromssystemets kontaktförhållanden och de relaterade utsläppen på modellskala. Validera resultaten på komponentnivå och förstå i vilken utsträckning de är betydande i full skala. Papper A undersöker påverkan av nominellt kontakttryck i en modellskala. Resultat visar att högre tryck motsvarar högre utsläpp. Papper B undersöker påverkan av det nominella kontakttrycket, för olika friktionsmaterial, i modellskala. En temperaturtröskel, för en emissionsökning identifieras. Papper C undersöker partikelegenskaper och slitagemekanismer för olika nominella kontakttryck, i en modellskala. Resultat visar ett förbättrat triboskikt vid högre trycknivåer. Papper D undersöker påverkan av bromssystemets förhållanden på utsläpp i en modellskala. Resultat visar att friktionskraften är den viktigaste parametern. En övergångstemperatur oberoende av kontaktförhållandet identifieras. Papper E undersöker likheter som uppträder på komponentskala och modellskala när det gäller emissioner. Resultatet visar en lovande korrelation, och möjligheten att använda en pinne-på-skiva-tribometer för FoU-aktiviteter. Papper F undersöker analogier som förekommer på en komponentskala och en modellskala, vad gäller friktionsprestanda, friktionsyta och kemisk sammansättning. Resultat visar liknande fenomen som förekommer för de två testskalorna. Papper G analyserar verkliga bromssystem arbetsförhållanden i en stadsmiljö som definierar, med hjälp av en tröghetsdyno bänk, de relaterade utsläppen. Resultatet visar utsläppsfaktorer som är förenliga med EURO6 och EURO2-reglerna, i fråga om antal respektive massa.
QC 20170808
REBRAKE Project
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Berry, David W. « Design, Analysis and Experimental Verification of a Mechanically Compliant Interface for Fabricating Reliable, Double-Side Cooled, High Temperature, Sintered Silver Interconnected Power Modules ». Diss., Virginia Tech, 2014. http://hdl.handle.net/10919/64898.
Texte intégralRésumé :
This research developed a double-side power electronics packaging scheme for high temperature applications exemplified by 1200 V, 150 A silicon devices. The power modules, based on both quarter and half-bridge topologies, were assembled using sintered silver device attachment rather than conventional solder alloys. Thermomechanical stresses in the double-side architecture were mitigated with a compliant layer fabricated from elliptical silver tubes.
This research presents an introduction to conventional packaging techniques and their weaknesses. These shortcomings provide the basis for a module design which improves upon module thermal management while also addressing electrical and reliability requirements. The optimum package design enhances heat dissipation with the addition of a substrate bonded to the top electrical pads of the semiconductor devices. The use of sintered silver also increases the useful application temperature by avoiding the creep failure mechanisms of solder alloys.
The modules were characterized extensively to quantify thermal and electrical performance. In the case of thermal characterization, the double-side architecture required multiple testing configurations to fully understand the parallel heat flow paths. These results were compared to models constructed using finite element analysis (FEA). The FEA models were also utilized for measurement of strains in multiple package designs to better determine the effects of increased compliance on the relative package cycling lifetime. These lifetimes were then assessed, in part, using experimental passive and cycling tests on functional double-side packages.
The resulting power modules exhibited significant decreases in thermal resistance when they are cooled, as designed, from both sides of the module. Even single sided cooling options reveal significant advantages and transient thermal impedance was found to be significantly lower. Power module models revealed the compliant layer was successful in reducing the device shear stresses which was experimentally validated through the use of DC power stage testing. It was found, through double pulse testing and electrical modeling, that parasitic inductances were reduced by utilizing planar bonding and planar symmetrical traces. Finally, modeling of the double-side package with added tube compliance revealed a decrease in plastic and shear strains when compared to other single and double-side package designs. This reduction directly translates to increased cycling lifetime using well known strain based fatigue models.Ph. D.
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So, Biu 1959. « THE METHODOLOGY AND IMPLEMENTATION OF RELAXATION METHOD TO INVESTIGATE ELECTRO-THERMAL INTERACTIONS IN SOLID-STATE INTEGRATED CIRCUITS ». Thesis, The University of Arizona, 1987. http://hdl.handle.net/10150/276384.
Texte intégral
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Landry, Karine. « Contribution à l'étude du mouillage réactif : étude du système aluminium/carbone ». Grenoble INPG, 1995. http://www.theses.fr/1995INPG0043.
Texte intégralRésumé :
La cinetique de mouillage et sa relation avec la reactivite interfaciale ont ete etudiees pour le systeme aluminium liquide/carbone en fonction des parametres suivants: temperature (entre 1000 et 1250 k), ordre microstructural des substrats de carbone et concentration en elements carburogenes (silicium, titane) dans l'aluminium. Le mouillage a ete etudie par la technique de la goutte posee. Le controle de l'etat de surface des substrats et la caracterisation des produits des reactions interfaciales ont ete realises par les techniques suivantes: microscopie electronique a balayage, microsonde electronique, diffraction des rayons x, profilometrie haute resolution, spectroscopie d'electrons auger et de photoelectrons x. Les conditions experimentales utilisees pour l'etude de la mouillabilite (preparation des echantillons, type du four et nature de l'atmosphere de travail) ont permis d'acceder a l'angle de contact et a l'energie d'adhesion intrinseques du systeme aluminium/carbone. Pour des temps de contact tres courts (interface non-reactive), l'aluminium ne mouille pas le carbone vitreux (l'interface est energetiquement faible). Puis, le mouillage s'ameliore consecutivement a la formation a l'interface d'une couche de carbure d'aluminium. La diminution de la temperature, l'augmentation de l'ordre microstructural du carbone et la presence de silicium dans l'aluminium modifient peu les angles de contact mais conduisent a un net ralentissement des cinetiques d'etalement et des vitesses des reactions interfaciales. De facon plus generale, l'analyse des resultats obtenus pour le systeme aluminium/carbone mais aussi pour un systeme modele (cuivre-silicium et cuivre-titane/carbone), nous a permis d'elucider les questions de la force motrice du mouillage et de la cinetique d'etalement dans les systemes reactifs
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Zhang, Rongwei. « Novel conductive adhesives for electronic packaging applications : a way towards economical, highly conductive, low temperature and flexible interconnects ». Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/39548.
Texte intégralRésumé :
Isotropically conductive adhesives (ICAs) are promising as a lead-free interconnect material; However, ICAs have a higher resistivity compared to tin/lead solder. The higher resistivity of ICAs results from the large contact resistance between conductive fillers. Several novel approaches to engineer the interface between electrically conductive fillers were studied to develop highly conductive ICAs. Shown in this dissertation are three methodologies to reduce contact resistance: low temperature sintering, fast sintering and in-situ reduction. Furthermore, two approaches, surface modification and in-situ protection, were developed to prevent oxidation and corrosion of silver-coated copper flakes to produce low cost ICAs. The findings and insights in this dissertation significantly contribute to (1) understanding of filler-filler, filler-polymer and structure-property relationships of ICAs; (2) the structural design and formulation of high performance ICAs; and (3) the wider use of ICAs in emerging applications such as printed electronics and solar cells.
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Almazan-Torres, Maria Guadalupe. « Effet de la temperature sur les mécanismes d'interaction entre l'ion uranyle et l'oxophosphate de zirconium ». Phd thesis, Université Paris Sud - Paris XI, 2007. http://tel.archives-ouvertes.fr/tel-00145065.
Texte intégralRésumé :
Dans le cadre des études sur le stockage de colis de déchets nucléaires, l'effet de la température sur les propriétés de rétention de l'ion uranyle sur Zr2O(PO4)2 a été étudié en milieu NaClO4 0,1 M. Dans un premier temps, l'effet de la température sur les propriétés acido-basiques de la surface (point de charge nulle, constantes d'acidité) a été suivi. Des expériences en réacteurs fermés ont été effectuées à des températures allant de 25°C à 90°C : la sorption des ions uranyle est favorisée avec l'augmentation de la température indiquant un processus de sorption de nature endothermique. La caractérisation des complexes de surface a été effectuée à l'aide des techniques spectroscopiques SLRT et EXAFS. Les mesures SLRT montrent la présence de deux complexes de surface différents. La nature de ces complexes ne se modifie pas avec le pH (3-5) ni la température (25°C-90°C). Par ailleurs, la spectroscopie EXAFS a mis en évidence la formation de complexes de sphère interne, bidentates. L'information structurale a été ensuite utilisée pour la modélisation des sauts de sorption. Pour le calcul des constantes de sorption, un modèle à capacité constante a été utilisé. Les équilibres de sorption modélisés ont révélé la formation des complexes de sorption : (>ZrOH)2UO22+ et (>PO)2UO2. La dépendance en température des constante de sorption a été ensuite utilisée pour déterminer les grandeurs thermodynamiques associées (ΔH° et ΔS°) par l'application de l'équation de van't Hoff. La variation d'enthalpie de formation du complexe (>ZrOH)2UO22+ est nulle, alors que celle du complexe (>PO)2UO2 est positive (55 kJ/mol), confirmant le caractère endotermique de la réaction de sorption.
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Jowkar, Saeid. « The Application of Programmable Logic Controller (PLC) to Control Temperature in Cold-room Based on TIA PORTAL Software ». Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020.
Trouver le texte intégralRésumé :
A temperature sensor is a device to measure the temperature through an electrical signal. It requires a thermocouple or resistance temperature detectors (RTD) and will interface with a programmable logic controller (PLC). A temperature transmitter is a device that connects to a temperature sensor to transmit the signal elsewhere for monitoring and control purposes that its role is to convert the temperature sensor's signal to a 0-10V DC voltage in the PLC. The PLC voltage signal setting is compared to the temperature deviation after the Proportional Integral Derivative (PID) operation. Then, the system will issue a temperature control signal to achieve the cooling system voltage control so that it implements continuous monitoring and temperature control. The temperature control system in the industrial field has a certain value that it is an important factor for controlling temperature. A certain value of the temperature of the desired environment has to be set with a minimum and maximum set-point temperature which is suitable for that environment and the set-point value can be variable and can be changed with Human Machine Interface (HMI) easily.
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Tyler, Samson. « Modelling the Effects of Element Doping and Temperature Cycling on the Fracture Toughness of β-NiAl / α-Al2O3 Interfaces in Gas Turbine Engines ». Thèse, Université d'Ottawa / University of Ottawa, 2013. http://hdl.handle.net/10393/23685.
Texte intégralRésumé :
This document describes work performed related to the determination of how elemental additions
affect the interfacial fracture toughness of thermal barrier coatings at the bond coat/thermally grown oxide interface in gas turbines. These turbines are exposed to cyclical thermal loading, therefore a simulation was designed to model this interface in a temperature cycle between 200 K and 1000 K that included oxide growth between 2 μm and 27 μm. The fracture toughness of this interface was then determined to elucidate the function of elemental additions. It was shown that minimal concentrations of atomic species, such as hafnium and yttrium cause notable increases in the toughness of the bond coat/thermally grown oxide interface, while other species, such as sulphur, can dramatically reduce the toughness. Furthermore, it was shown that, contrary to some empirical results, the addition of platinum has a negligible effect on the fracture toughness of this interface.